macOS venv creation via copy fails

[gaborbernat]

❯ python3.13 -m venv --copies venv --clear
Error: Command '['/Users/bgabor8/git/github/virtualenv/venv/bin/python3.13', '-m', 'ensurepip', '--upgrade', '--default-pip']' died with <Signals.SIGABRT: 6>.

❯ venv/bin/python 
dyld[94922]: Library not loaded: @executable_path/../lib/libpython3.13.dylib
  Referenced from: <4C4C4407-5555-3144-A1FE-AA5FDFE2B24E> /Users/bgabor8/git/github/virtualenv/venv/bin/python
  Reason: tried: '/Users/bgabor8/git/github/virtualenv/venv/lib/libpython3.13.dylib' (no such file)
fish: Job 1, 'venv/bin/python' terminated by signal SIGABRT (Abort)

Only happens on macOS, not Linux and Windows. Works when using symlink mode, unclear if related to #381

(This breaks the virtualenv test suite at https://github.com/pypa/virtualenv/actions/runs/16404089042/job/46347551787?pr=2904)

[geofft]

I think this is indeed the same as #381, we're currently linking libpython statically on Linux but not macOS (#636).

But I think this is genuinely a bug in virtualenv and venv: if run against an interpreter that dynamically links libpython, --copies needs to copy libpython, or run patchelf/install_name_tool or equivalent, or not exist. Note that Apple chose the last option for their builds of Python.